Hypoxemia is a below-normal level of oxygen in your blood, specifically in the arteries. Hypoxemia is a sign of a problem related to breathing or circulation, and may result in various symptoms, such as shortness of breath.

Hypoxemia is determined by measuring the oxygen level in a blood sample taken from an artery (arterial blood gas). It can also be estimated by measuring the oxygen saturation of your blood using a pulse oximeter — a small device that clips to your finger.

Causes

Several factors are needed to continuously supply the cells and tissues in your body with oxygen:

- There must be enough oxygen in the air you are breathing

- Your lungs must be able to inhale the oxygen-containing air — and exhale carbon dioxide

- Your bloodstream must be able to circulate blood to your lungs, take up the oxygen and carry it throughout your body

When to see a doctor

Seek emergency care if you have:

Severe shortness of breath that comes on suddenly and affects your ability to function.

Severe shortness of breath with a cough, rapid heartbeat and fluid retention at high elevations (above 8,000 feet, or about 2,400 meters). These are signs and symptoms of fluid leaking from blood vessels into your lungs (high-altitude pulmonary edema), which can be fatal.

See your doctor as soon as possible if you have:

Shortness of breath after slight exertion or when you're at rest

Shortness of breath that gets worse when you exercise or are physically active

Abrupt awakenings with shortness of breath or a feeling that you're choking — these may be symptoms of sleep apnea

Self-care

To cope with chronic shortness of breath, try to:

Stop smoking. If you've been diagnosed with COPD or another lung disease, the single most important thing you can do is to quit smoking.

Avoid passive smoke. Avoid places where others smoke. Secondhand smoke can cause further lung damage.

Get regular exercise. It may seem difficult to exercise when you have trouble breathing, but regular exercise can improve your overall strength and endurance.